Applicant is aware of the following related U.S. Pat. Nos. 4,042,196 to Quirk et al; 1,517,587 to Roth; 1,999,213 to Shaler; 2,144,382 to Lincoln et al; 2,839,943 to Caldwell et al; 2,897,734 to Bodine, Jr.; 3,417,966 to Bodine; 3,630,357 to Nolte; 3,640,508 to Reibig; 4,784,088 to Tamba et al and 4,793,196 to Davis et al.
Shakers or vibrators have been known for many years, however, such shakers have various limitations and disadvantages. Various types of counter rotating shakers have been suggested throughout the years, however most of these shakers require substantial maintenance and have reliability problems. Noise of the gears in rotary shakers is also a significant problem. Lubrication of gears and bearings is another problem especially due to contamination of the product by oil when used in the food or drug industry.